Medical Pump

ABSTRACT

The invention relates to a medical pump, especially for water jet surgery, in which a pump unit assembled as a single use article can be reversibly connected to a pump actuating device. In order to simplify one such arrangement, the pump actuating device is also used to open up the connection between the pump unit and the pump actuating device.

The invention refers to a medical pump, in particular for water jetsurgery.

Water jet surgery has been used for some time in liver surgery, as thisorgan has tissue structures of different firmness (parenchyma, bloodvessels and bile ducts) like no other and the applied water jetseparates the tissue being cut (parenchyma) yet leaves the blood vesselsand bile ducts undamaged. Naturally, precise control of the cuttingpressure is required for this.

A further problem with water jet surgery is that the cutting medium mustbe totally sterile (e.g. Ringer solution), as the liquid comes intocontact with body tissue in the closest and most intensive way possible.Ordinary problems such as high reliability, simplicity and economicmanufacture must also be considered.

Medical pumps for water jet surgery are known from U.S. Pat. No.6,216,573 B1 and DE 203 09 616 U1, which comprise an exchangeable pumpunit for single use, which can be connected to pump actuating devices.Changing of the pump devices is, however, very costly with the knownsetups. As relatively large forces are needed to generate high pressurewith sufficient flow, the devices for connection of the pump device tothe pump actuating devices must be very substantial so that they canmaintain a “firm hold” on the pump device.

The object of the invention is to develop a medical pump of the typedescribed initially, so that the connection between the pump unit andthe pump actuating device is improved and easier to operate.

The object is achieved by a medical pump according to claim 1. Theobject is achieved in particular by a medical pump, in particular forwater jet surgery comprising the following:

-   -   a pump unit which is assembled as a single use article with at        least one piston with a piston rod for displacing the piston in        an allocated cylinder,    -   a pump actuating device with at least one drive device and one        motor control for actuation of the pump unit by displacing the        piston rod,    -   holding devices which can be opened and closed for reversible        attachment of the pump unit to the pump actuating device,    -   clutch devices which can be opened and closed for reversible        connection of the piston rods to the drive device, wherein the        drive device is constructed to actuate in a controllable manner,        in particular the opening and/or closing of the holding devices        and/or the clutch devices.

An essential point of the invention is that the drive device which isactually envisaged for pushing the piston back and forth additionallyactuates or controls the holding devices and/or the clutch devices aswell. Simple operation (by means of the drive device) is thusguaranteed; on the other hand a large holding force can be exerted, asthis is applied during opening for decoupling of the pump unit from thepump actuating device and not by the user.

The holding devices and/or the clutch devices comprise preferably snapfittings, which are constructed in such a way that closing of theholding devices and/or clutch devices can be achieved by snapping inplace and opening by means of the drive device by opening the snapfittings. The energy required for connecting the pump device to thedrive device can be generated with longer travel at a greater holdingforce very easily by the user. Otherwise opening is then carried out bythe drive devices with a corresponding large holding force, so that onlyopening must be carried out by the drive devices but not closing aswell. This simplifies the setup.

The snap fittings are preferably constructed in such a way, that theforce required for closing is less than that for opening.

The drive device is preferably constructed in such a way that theengagement devices fitted in the clutch devices are positioned at restprior to attaching the pump unit to the pump actuating device in such away that on connecting the pump unit to the pump actuating device theengagement devices disengage from the piston rods and the clutch devicescan be closed by actuating the drive devices. This means that the userdoes not have to carry out any great manipulation in relation to thepistons or piston positions in order to attach the pump unit to the pumpactuating device.

It is preferable if two pistons with piston rods are provided in thecylinders and the pump actuating device is constructed to give alternatedisplacement of the pistons. An increased pump performance can thus beensured. In this embodiment the pump actuating device is constructedwith two motors or a motor with controllable gearing preferablycontrollable in such a way that the pistons can be displacedsynchronously for alternate opening or closing of the holding deviceand/or the clutch devices. While during normal pump operation thepistons are operated alternately a different modus operandi is selectedfor opening and closing of the holding device and/or the clutch deviceswith the same drive set which results in a simplified setup.

The drive device comprises preferably a linear drive (or with twopistons, two linear drives) with shaft and motor so that the shaft isdrivable in a controllable manner. Very accurate movements can becarried out via such linear drives, thereby protecting the pump with itspiston/cylinder units.

The motor control is preferably constructed in such a way that thepistons can be displaced at a constant speed. This results in a smootherdelivery of the medium to be pumped.

Preferred embodiments of the invention result from the sub-claims.

Below, preferred embodiments of the invention are explained in moredetail with the aid of illustrations. These depict:

FIG. 1 a schematic block diagram of an embodiment of the medical pump,

FIG. 2 an exploded diagram of an embodiment of the pump,

FIG. 3 a perspective diagram of the pump actuating device with coupledpump unit,

FIG. 4 a side view of the holding device,

FIG. 5 an illustration similar to FIG. 4, but in a part-sectioneddrawing along line V-V from FIG. 6,

FIG. 6 an illustration of the setup according to FIG. 4 in plan view,

FIG. 7-9 illustrations corresponding to those in FIG. 4-6, but with theholding device in an open position,

FIG. 10 an exploded drawing of the functional units of the holdingdevice,

FIG. 11 a perspective diagram of a sub-unit from FIG. 10,

FIG. 12 an exploded drawing of a sub-unit from FIG. 11,

FIG. 13 a perspective drawing of the clutch devices,

FIG. 14 an illustration of the clutch devices from FIG. 13 in adifferent displacement position,

FIG. 15 an exploded drawing of a clutch device from FIG. 13 or 14,

FIG. 16 an exploded illustration of the sub-unit of the setup accordingto FIG. 13,

FIG. 17 a plan view of the setup according to FIG. 13 with coupledpiston rods,

FIG. 18 a front view of the setup according to FIG. 17,

FIG. 19 a view according to FIG. 17, but in a different operationalstate,

FIG. 20 a front view onto the setup according to FIG. 19,

FIG. 21 a section along line XXI-XI from FIG. 19.

The same reference numbers will be used for the same parts and for partswith the same function.

In the embodiment of the invention depicted in FIG. 1 a pump actuatingdevice 10 is provided which encompasses a motor control 15 for thecontrol of two motors 11, 11′, which are connected via gearing 12, 12′and clutch devices 13, 13′ to the piston rods 25, 25′. An operator B canoperate the motor control 15 by means of suitable switches (foot switchor finger switch) so that the motors 11, 11′ alternately displace thepiston rod 25, 25′ and thus the pistons 22, 22′ in the cylinders 21, 21′of a pump unit 20 via the described train, so that the volume of thepressure chambers 16, 16′ of the pump unit 20 is alternately enlargedand reduced.

In order to seal the pressure chambers 16, 16′ and the pistons 22, 22′in relation to the cylinders 21, 21′ seals 23, 23′ are envisaged at thepistons 22, 22′. Moreover, the piston rods 25, 25′ maintain sterilitywith cup seals 24, 24′, which are firmly fixed to the cylinders 21, 21′on the one hand and to the pistons rods 25, 25′ on the other. In thisway germs from the ambient air which without these cup seals 24, 24′settle on the internal walls of the cylinders 21, 21′ and pass throughthe seals 23, 23′ can neither mix with the working fluid nor find theirway into the same.

Suction valves 26, 26′ as well as pressure valves 27, 27′ are connectedto the pressure chambers 16, 16′. The suction valves 26, 26′ areconnected via a fluid inlet 6 to a reservoir 9 for the working fluid.The pressure valves 27, 27′ are connected to the pressure hose 5 whichleads to an applicator 8 via a fluid outlet 7. The pump unit 20 forms adisposable part E together with the reservoir 9 including its contents,pressure hose 5 and applicator 8, which is disposed of after eachoperation, so that the entire setup meets the highest sterilityrequirements possible.

A butterfly valve 14 is provided by means of which (in addition to themotor control 15) operator B can switch off the fluid flow completely.The embodiment of the invention shown in FIG. 1 is a pressure controlvalve 35 which with the aid of a valve membrane 36 can open and close aconnecting channel between fluid outlet 7 and fluid inlet 6. Themembrane 36 is operated by an actuator 30 via a push rod 34 and a spring33 as well as a dynamometer 31. The dynamometer 31 supplies a powerproportional output signal to a controller 32, by means of which anoperator B can set a maximum pressure. Instead of a separate dynamometer31 the operating current of the actuator 30 can be measured which isalso power proportional.

This layout guarantees that the fluid pressure can be accuratelyadjusted at the applicator 8. Moreover, pressure fluctuations resultingfrom piston operation are smoothed out by the control valve 35. Theimportant point is that the pressure control valve 35 due to itsconstruction operates with the membrane pressurised by fluid in apower-controlled and not a travel-controlled manner. No pressureadjustment error can therefore occur during coupling of the pump unit 20to the pump actuating device 10 even with dimension tolerances as it isnot the geometric dimensions (travel) which are important, but the powerwith which the pressure control valve 35 is operated.

FIG. 2 shows an exploded view of a construction embodiment of the pumpdevice 20. In this embodiment the pressure and suction valves 26/27encompass balls 19 which are pressed onto the valve seats via springs 18(not visible in the illustration) which principle is known.

The cylinder head 29 has two sections to which the cylinders 21, 21′ arecoupled, whereby the valves sit between the cylinders 21, 21′ and thecylinder head 29.

It can further be seen from FIG. 2, that the piston rods 25, 25′ havecoupling projections 17, 17′ at their distal ends which serve to createa mechanical connection with the coupling systems 13, 13′.

The pistons in this embodiment of the invention are formed by theproximal ends of the piston rods 25, 25′ fitted with caps 28, whichsimultaneously hold seals 23, 23′ firmly on the piston rods 25, 25′.

The pressure hose 5 is fastened irreversibly to the cylinder head 29 viaa connecting piece 37, a crimping piece 38 and an internal pipe which isinserted into the pressure hose 5, whereby after assembly (in a knownway) the connecting piece 37 is held in the cylinder head 29 by means ofa catch 45 which holds the connecting piece 37 irreversibly in thecylinder head 29.

FIG. 3 shows a perspective illustration of the pump actuating device 10with a coupled pump unit 20. This illustration shows that the pumpactuating device has a frame 65 to which the motors 11, 11′ areattached. They are constructed as reversing motors which drive theshafts 47, 47′ via cog belts 48, 48′ and gearing 12, 12′, so that therotary movement of the motors 11, 11′ is translated into a linearmovement. Attached to the shafts 47, 47′ are the clutches 13, 13′ towhich the piston rods 25, 25′ can be coupled. The setup of the actuator30 with the relevant push rod 34 is also visible in this illustration.

Moreover, the holding device 50 is attached to the frame 25 which isintended for holding the pump unit 20.

The holding device is explained in more detail with the aid of FIG. 4 -12.

The holding device 50 encompasses jaw holder 52, 52′ with jaws 51, 51′at the end which are constructed in such a way that they can engage withthe lugs 46 provided in order to hold the pump unit 20.

The jaw holders 52, 52′—as shown in FIG. 4—are positioned on the frame65 via swivel pins and pretensioned in the closed position (FIG. 4-6) bymeans of springs 53 (see FIG. 10). In order to insert a pump unit 20this is pushed into the holding device 50 in such a way that the jaws51, 51′ slip with front inclined surfaces over the lugs 46 of the pumpunit 20 and are forced onto it. When the pump unit 20 has then beenfully pushed on, the jaw holders 52, 52′ snap shut and the jaws 51, 51′hold the pump unit 20 in this position until they are pushed apartagain.

The mechanism for opening the holding device 50 or jaws 51, 51′ isexplained with the aid of FIG. 10-12.

The holding device 50 encompasses a holding block 54, which has cylinderhousings 56, 56′ at its front which correspond to the rears of thecylinders 21, 21′ of pump unit 20. The fit can be seen easily when FIG.2 and 10 are compared.

An opening slide 57 is fixed with fastening screws 59, 59′ to thecylinder housing 56, whereby the opening slide 57 has elongated holes60, 60′ so that it can be pushed back and forth. The opening slide 52 ispushed backwards, away from the pump unit 20, by means of a spring 58.

A rocker 52 which can be swivelled back and forth is fixed to theopening slide 57 by means of a rocker bearing 63 carrying symmetricallyarranged tongues 64, 64′. The opening slide 57 has an opening tongue 61at its front facing the pump unit 20. The opening tongue 61 has a heightwhich corresponds to the distance between the internal surfaces of thejaw holders 52, 52′. On these inner surfaces of the jaw holders 52, 52′opening ramps 55, 55′ have been attached in the displacement path of theopening tongue 61 in such a way that the opening tongue 61, on meetingthe opening ramps 55, 55′ and during further displacement in thedirection of the pump unit 50, pushes apart the jaw holders 52, 52′, sothat they change from the position shown in FIG. 4-6 to the position inFIG. 7-9. In this position (according to FIG. 7-9) the jaws 51, 51′disengage from the lugs on the pump unit 20 thus releasing it.Displacement of the opening slide 57 occurs as described as follows.

During a “normal” operation of the pump unit 20 the shafts 47, 47′ aremoved back and forth alternately, so that in an end position of a shaft47 or 47′ they hold the positions shown in FIG. 6 or 10. During thesemovements the holding blocks 72, 72′ are moved by the piston holders 70,70′ at the end of the shafts 47, 47′ past the tongues 64, 64′ in such away that the rocker 62 is either tilted anti-clockwise, as shown in FIG.6 or 10, or in the other direction in which the holding blocks 72, 72′are in the reverse position—projecting or pulled back. These alternatingmovements of the piston holders 70, 70′ or the holding blocks 72, 72′can thus be carried out to operate the pump without displacing theopening slide 57 in the direction of the pump unit 20.

But when the shafts 47, 47′ are driven in such a way that both pistonholders 70, 70′ or holding blocks 72, 72′ run side by side, the rocker62 cannot be avoided during displacement (in the direction of the pumpunit 20), so that both holding blocks 72, 72′ engage simultaneously withboth holding tongues 64, 64′. As a result the opening slide 57 is pushedagainst the force of the spring 58 in its elongated holes 60, 60′ in thedirection of the pump unit 50 when the piston holders 70, 70′ continueto move forward so that the opening tongue 61 slides over the openingramps 55, 55′ thus forcing the jaw holders 52, 52′ apart. The engagementof the jaws 51, 51′ in relation to the lugs 46 on the pump unit 20 isreleased as a result. This opening of the holding device 50 thus occursexclusively by means of the motors 11, 11′ and their correspondingcontrol by means of the motor control 15.

Below the effect or actuation of the clutch systems 13, 13′ is describedin more detail with which the piston rods 25, 25′ are coupled to thepiston holders 70, 70′ via their coupling projections 17, 17′. Attentionis drawn in this respect to FIG. 13-21.

The holding blocks 72, 72′ are screwed onto the shafts 47, 47′ as shownin FIG. 15 and comprise insertion openings 77, 77′ into which the pistonrods 25, 25′ can be inserted with their coupling projections 17, 17′.Springs 71, 71′ are attached to the holding blocks 72, 72′ in such a waythat the spring ends 73, 73′ protrude into the insertion openings 77,77′. The distance of the spring ends 73, 73′ is such that the pistonrods 25, 25′ can be inserted into the insertion openings 77, 77′ withtheir coupling projections 17, 17′ and force the spring ends 73, 73′apart until they snap shut behind the coupling projections 17, 17′. Forthis the coupling projections 17, 17′ have conical ends. After insertingthe coupling projections 17, 17′ into the piston holders 70, 70′ thepiston rods 25, 25′ are connected to the piston holders 70, 70′ and canneither be pushed nor pulled.

Between the displacement travel of the piston holders 70, 70′ or theholding blocks 72, 72′ a straddle lever 74 is attached on a swivelbearing 75 so that it can tilt, where on its upper and lower side it hasstraddle surfaces 76, 76′ on the side facing away from the pump unit 20.On the other end, the end facing the pump unit 20, swivel edges 78, 78′are constructed on the straddle lever 74.

The layout and dimensioning of the straddle lever 74 with its straddlesurfaces 76, 76′ and swivel edges 78, 78′ is such that with alternatingmovements of the holding blocks 72, 72′ or piston holders 70, 70′, asshown in FIGS. 13 and 17, the straddle lever 74 is tilted either to oneside or to the other side depending on which of the piston holders 70,70′ or holding blocks 72, 72′ slide past it in the direction of the pumpunit 20. As result of this swivel action the straddle surfaces 76, 76′are swivelled in such a way that they do not engage with the spring ends73, 73′ of the piston holder 70 or 70′ as they slide past. But when bothpiston holders 70, 70′ are pushed parallel next to each other in thedirection of the pump unit 20 (see FIG. 14 and 19-21) the straddlesurfaces 76 or 76′ engage with the spring ends 73, 73′ (see inparticular FIG. 20 and 21) so that these slide along on the (chamfered)straddle surface 76 or 76′ and are forced apart. As a result of thisforcing apart the piston rods 25, 25′ previously attached to theircoupling projections 17, 17′ (see holding position according to FIG. 18)are released as shown in FIG. 20. After this with the same andsimultaneous parallel movement of the piston holders 70, 70′ or holdingblocks 72, 72′ the holding device 50 as well as the jaws 51, 51′ areforced open and thus their engagement with the lugs 46 of the pump unit20 is released, the pump unit can be removed by the paralleldisplacement of the piston holders 70, 70′ as far as their frontposition facing the pump unit 20 without the user having to overcome anyforce.

The motor control 15 is furthermore constructed in such a way that afterremoval of a pump unit 20 from the pump actuating device 10 both shafts47, 47′ retract the piston holders 70, 70′. If the user inserts the pumpunit 20 into the pump actuating unit 10, it is only the force requiredfor opening the holding device 50 that needs to be overcome. The pistonrods 25, 25′ then protrude with their coupling projections 17, 17′through the cylinder housing 56, 56′ into the pump actuating device 10.The user can now control the motor 15 in such a way that the same movesthe piston holders 70, 70′ in the direction of the pump unit 20 in a“coupling mode” until the coupling projections 17 or 17′ push apart thespring ends 73, 73′ and snap shut. This snapping process is carried outseparately one after the other for both coupling projections 17 or 17′,so that the straddle lever 74 does not open the springs 71, 71′.

It becomes clear from the above description that the essential point ofthis invention is, that coupling of the pump unit 20 to the pumpactuating device 10 occurs partially and decoupling occurs completelyvia the drive, which is itself actually envisaged for actuation of thepump. Separate drive devices are therefore not required.

REFERENCE LIST

-   E Disposable part-   B Operator-   5 Pressure hose-   6 Fluid inlet-   7 Fluid outlet-   8 Applicator-   9 Reservoir-   10 Pump actuating device-   11, 11′ Motor-   12, 12′ Gearing-   13, 13′ Clutch system-   14 Butterfly valve-   15 Motor control-   16, 16′ Pressure chamber-   17, 17′ Coupling projection-   18 Spring-   19 Ball-   20 Pump unit-   21, 21′ Cylinder-   22, 22′ Piston-   23, 23′ Seal-   24, 24′ Cup seal-   25, 25′ Piston rod-   26, 26′ Suction valve-   27, 27′ Pressure valve-   28 Cap-   29 Cylinder head-   30 Actuator-   31 Dynamometer-   32 Controllers-   33 Spring-   34 Push rod-   35 Pressure control valve-   36 Valve membrane-   37 Connecting piece-   38 Crimping piece-   39 Internal tube-   45 Catch tongue-   46 Lugs-   47, 47′ Spindle-   48, 48′ Cog belt-   50 Holding device-   51, 51′ Jaws-   52, 52′ Jaw holder-   53 Pressure spring-   54 Holding block-   55, 55′ Opening ramp-   56, 56′ Cylinder housing-   57 Opening slide-   58 Spring-   59, 59′ Attachment screw-   60, 60′ Elongated hole-   61 Opening tongue-   62 Rocker-   63 Rocker bearing-   64, 64′ Tongues-   65 Frame-   70 Piston holder/Engagement devices-   71, 71′ Spring-   72, 72′ Holding block-   73, 73′ Spring ends-   74 Straddle lever-   75 Bearing-   76, 76′ Straddling surfaces-   77, 77′ Insertion openings-   78, 78′ Swivel edges

1. Medical pump comprising a pump unit which is assembled as a singleuse article and which comprises at least one piston and piston rod fordisplacing the piston in an allocated cylinder defined by the pump unit;a pump actuating device comprising at least one controllable drivedevice and a motor control adapted to actuate the pump unit bydisplacing the piston rod; holding devices which are adapted to open andclose for reversible attachment of the pump unit to the pump actuatingdevice; and clutch means which are adapted to open and close forreversible connection of the piston rod to the drive device; the drivedevice being adapted to actuate the opening or closing of at least oneof said holding devices or said clutch means.
 2. Medical pump accordingto claim 1, wherein at least one of said holding devices or said clutchmeans comprises a snap device adapted to operate by snapping shut andopening by means of said drive device (11, 12) by opening said snapdevice.
 3. Medical pump according to claim 2, wherein said snap deviceis constructed such that a force needed to close it is lower than aforce needed to open it.
 4. Medical pump according to claim 1, whereinsaid said holding devices of said clutch means comprise engagement meanswhich are fitted in said pump actuating device and which are positionedin a rest position prior to attachment of said pump unit to said pumpactuating device whereby on connection of said pump unit to said pumpactuating device the engagement means are disengaged from said pistonrods and said clutch devices are closable by actuation of each drivedevice.
 5. Medical pump according to claim 1, wherein two pistons andpiston rods are provided in cylinders and said pump actuating devicealternately displaces said pistons.
 6. Medical pump according to claim5, wherein said controllable drive device for said pump actuating devicecomprises motor means which displaces said pistons such that saidpistons are displaced alternate synchronous opening or closing of theholding device (46, 50) and/or the clutch devices (13).
 7. Medical pumpaccording to claim 1, wherein said controllable drive device comprises alinear drive having at least one shaft and at least one motor forcontrollable driving of said the shaft.
 8. Medical pump according toclaim 1, wherein said motor control displaces said pistons at a constantspeed.